Alexander's Army by Chris d'Lacey

Invisibly bound to an organisation that deals with the extraordinary and previously thought impossible, Michael has no choice other than to accept an important mission which brings him further from comfort but closer to truth about the organisation and his long last father. In this second book of the UNICORNE Files, Michael's mission involves peculiar happenings in a local comic book shop. Little does he know that these peculiar happenings have been designed to lure him in.